边界折叠:折叠; 应该将两个相同的相邻边界合并在一起.在html2pdf中使用它时，应同时设置 border-left 和 border-right 属性的样式(相同)，折叠时将产生单个边框.另外，要防御性地编写此CSS，而不假定 border-color 属性是继承的，则应在定义边框时从技术上指定它，例如 border:1px纯黑；

border-collapse: collapse; is supposed to merge two of the same, adjacent borders together. When using it in html2pdf, you should style both the border-left and border-right attributes (as the same thing), which when collapsed will produce a single border. Also, to write this CSS defensively, and not assume the border-color attribute inheritance, you should technically specify it when defining border, such as border: 1px solid black;